foam cutter

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Project by bobasaurus posted 04-08-2011 03:04 AM 5067 views 9 times favorited 4 comments Add to Favorites Watch

I made this foam cutter for work (got paid to woodwork in my garage for a day :). I build weather balloon instruments that require lots of foam insulation to keep things warm at 30 km (100k feet) altitudes. We used to hack out foam parts by hand with a knife, and also had a kludged-together foam cutter that wasn’t very reliable, so things were pretty ugly and difficult to produce. Now we can use this thing sort of like a combination bandsaw (long “blade” we can use for tall foam), router table (we trace the pattern around jigs to cut out fancy shapes), table saw (there’s a rockler fence with t-track), and jointer (you can set the fence close and push crooked foam against it while sliding to “joint” an edge) for foam. I wish the same tool could be used to cut wood! It works with a variac (variable AC voltage source) hooked up to a long piece of steel wire stretched vertically from the table to the upper arm. As the wire gets hot it tends to stretch, so I put a simple spring tensioning system on the top. There’s a little metal collet inserted at the bottom to keep the base table from burning too badly. The fifth picture shows one of the jigs we use to cut out a U shape, along with a jigsaw puzzle for fun (they make good souvenirs for visitors). Overall, this tool has greatly sped up our instrument production and reproducible quality. The whole thing is in a fume hood for safety, as melting foam makes some pretty terrible vapors.

I used red oak (usually two 4/4 pieces laminated) for the upper arm and a frame that holds up a melamine / particle board table. Mostly used pocket hole joinery.

-- Allen, Colorado (Instagram @bobasaurus_woodworking)

4 comments so far

View Chefshep's profile


121 posts in 4141 days

#1 posted 04-08-2011 04:07 AM

Very interesting… I first heard about foam cutters a few months ago, while I was researching sound proofing. Looks like you did a great job.

-- Chefshep :) "When we allow our present to quarrel with our past, we risk jeopardizing our future.” - Winston Churchill

View RPersad's profile


15 posts in 4151 days

#2 posted 04-08-2011 04:22 AM

Well done. i love shop-made jigs, tools and machines and this one seems to do its job quite well. Plus u got paid for a day in the shop…seems win-win to me. lol.

-- Measure Twice Cut Once -- It's a lot easier to cut more off than it is to cut MORON.

View Omegacool's profile


83 posts in 5089 days

#3 posted 04-08-2011 08:59 AM

I have one similar to cut Styrofoam to insulate doors, but ugly, this is nice.

-- Sorry I do not speak English very well, nor write, but I learn

View steliart's profile


2895 posts in 4146 days

#4 posted 04-08-2011 06:18 PM

Probably the best I’ve seen so far
well done

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions !!!

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